Paste-like and film-like anisotropic conductive materials are widely known. In the anisotropic conductive material, a plurality of conductive particles are dispersed in a binder resin.
The anisotropic conductive material is used for, for example, connection of a flexible printed circuit board and a glass board (FOG (Film on Glass)), connection of a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), connection of a semiconductor chip and a glass board (COG (Chip on Glass)), connection of a flexible printed circuit board and a glass epoxy board (FOB (Film on Board)) and so on in order to obtain various kinds of connection structures.
For example, when an electrode of a semiconductor chip and an electrode of a glass board are electrically connected by the anisotropic conductive material, an anisotropic conductive material including conductive particles is arranged on the glass board. Next, the semiconductor chip is laminated, and the laminate is heated and pressurized. The anisotropic conductive material is thereby cured, so that the electrodes are electrically connected via conductive particles to obtain a connection structure.
As one example of the anisotropic conductive material, Patent Documents 1 and 2 disclose an anisotropic conductive material including a thermosetting binder, solder particles having a melting point of 180° C. or lower or 160° C. or lower, and a flux component. As the flux component, a compound represented by the following formula (101) or (102) is used. The anisotropic conductive material described in Patent Document 1 essentially includes an epoxy resin and a cationic curing initiator as the thermosetting binder. Patent Documents 1 and 2 describe that a flux component and a solder particle are chelate-coordinated.

In the formula (101) and the formula (102), R1 to R4 each represent a hydrogen atom, an alkyl group or a hydroxyl group; X represents an atomic group having a lone electron-pair or a double bond π electron with which a metal can be coordinated; and Y represents an atom or an atomic group that forms a main chain backbone. In Patent Document 2, Y in the formula (101) and the formula (102) represents an alkyl group.
Patent Document 3 discloses a solder ball coated on the surface with at least two organic acids having 10 to 25 carbon atoms and having a carboxyl group. In the solder ball, the carboxyl group of the organic acid is chelate-coordinated with the surface of the solder ball.
Patent Document 4 discloses a solder powder coated by chemically bonding at least one of a fatty acid and a dicarboxylic acid to the surface. Patent Document 4 discloses a conductive adhesive (anisotropic conductive material) including the solder powder, a resin and a curing agent.